中空节流孔式空心阴极触发点火启动过程的气体击穿放电机理及设计优化研究

As novel space propulsion technologies which have been widespread used in the field of high-value spacecraft, ion and Hall electric thrusters are one of the essential means to support spacecraft upgrading and improving international competition for our country. The hallow cathode is a single failure component of the electric propulsion whose ignition number is a key issue which influences the spacecraft lifetime. At present, the broken through high-temperature heater technology of novel orificed LaB6 cathode has achieved the lifetime limitation due to material high temperature tolerance thus makes it difficult to further improve the cathode lifetime. It is extremely necessary to study the basic physics problems of flow field distribution, original electrons mobility, gas breakdown between the propellant and electrodes, discharge extension microprocess referring to breakdown between of LaB6 hallow cathode ignition electrodes, and solve the optimization design technology problem of the ability to switch tens of thousands of times for hallow cathode. With decades of technical tackling, our research group has recognized the essential parameters which could influence the ignition number lifetime of the hallow cathode. However, the influence results are not quantized and the engineering design is not optimal yet due to the lack of mechanism understanding behind that problem. The completion of this project can provide the basic theory supporting to long-lifetime optimization design of hallow cathode for space propulsion, and makes contributions to further expanding the research fields of gas discharge in our country.

离子和霍尔电推进作为新型空间推进技术在高价值航天器领域具有广泛的应用前景，是支撑我国航天器更新换代和提升国际竞争力的重要手段之一。空心阴极作为电推进系统单点失效组件，具备的点火次数寿命是影响航天器在轨寿命的关键问题。目前，已经突破的新型中空节流孔式LaB6空心阴极高温加热器技术，基本达到了材料高温服役寿命极限，加热器预热开关次数寿命难以提高。有必要对LaB6空心阴极点火电极间击穿涉及的流场分布、原初电子迁移、工质气体流场和电极间气体击穿及放电扩展过程等基础科学问题进行研究，解决空心阴极数万次开关能力优化设计技术问题。课题组经过十数年技术攻关，已经识别了影响空心阴极点火次数寿命的关键参数，由于始终未能掌握问题背后的科学机理，无法量化其影响使工程设计达到最优。本项目的完成，可以为我国空间电推进空心阴极长寿命点火优化设计提供基础理论支撑，同时为进一步拓展我国气体放电研究领域做出贡献。

航天发展，动力先行。空间电推进相比传统化学推进具有效率高、比冲高、寿命长和推力精确可调节等优点，是提高卫星综合效能、实现航天器更新换代和提高国际竞争力的重要手段，离子电推进和霍尔电推进是目前广泛应用的空间电推进类型，作为电子源中空节流孔式空心阴极被喻为电推进的“心脏”。空心阴极作为电推进系统单点失效组件，具备的点火次数寿命是影响航天器在轨寿命的关键问题。目前，已经突破的新型中空节流孔式LaB6空心阴极高温加热器技术，基本达到了材料高温服役寿命极限，加热器预热开关次数寿命难以提高。有必要对LaB6空心阴极点火电极间击穿涉及的流场分布、原初电子迁移、工质气体流场和电极间气体击穿及放电扩展过程等基础科学问题进行研究，解决空心阴极数万次开关能力优化设计技术问题。.本项目研究内容包括四项，1）中空节流孔式空心阴极点火预热下工质气体流场特性研究 ；2）中空节流孔式空心阴极真空电子发射理论分析及验证；3）工质气体流场对 LaB6 发射体原初电子发射动态发展特性影响试验研究；4）点火脉冲电源作用下工质气体击穿过程仿真及验证。.通过构建中空节流孔式空心阴极点火预热下工质气体流场仿真模型和原初电子迁移规律研究，结合光谱方法，验证了原初电子迁移规律，并对中空节流孔式空心阴极击穿过程快速成像结果分析，掌握了发射体温度、阴极顶节流小孔孔径、触持极间距、工质流率和外部磁场等对中空节流孔式空心阴极点火击穿过程的影响规律，形成了中空节流孔式空心阴极优化点火设计准则，指导了3A、5A和20A电子发射电流空心阴极设计，5A和20A空心阴极已经在XX-20和XX-6D卫星上在轨飞行验证和应用，点火时间满足在轨任务需求，在规定点火时间内，点火成功率达到100%。.后续，本项目支持研究的中空节流孔式空心阴极将应用于我国深空探测、高轨通信、低轨卫星星座等任务，对提升我国卫星系统整体效能和商业卫星国际竞争力具有支持意义。